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Complete separation along matrilines in a social spider metapopulation inferred from hypervariable mitochondrial DNA region

Authors

  • I. AGNARSSON,

    1. Institute of Biology, Scientific Research Centre of the Slovenian Academy of Sciences and Arts, Novi trg 2, PO Box 306, SI-1001 Ljubljana, Slovenia
    2. Department of Biology, University of Puerto Rico, PO Box 23360, San Juan, PR 00931-3360, USA
    3. Department of Zoology, The University of British Columbia, 2370-6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada
    4. Department of Botany, The University of British Columbia, 3529-6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada
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  • W. P. MADDISON,

    1. Department of Zoology, The University of British Columbia, 2370-6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada
    2. Department of Botany, The University of British Columbia, 3529-6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada
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  • L. AVILÉS

    1. Department of Zoology, The University of British Columbia, 2370-6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada
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I. Agnarsson, Fax: 787 7642610; E-mail: iagnarsson@gmail.com

Abstract

The distribution and quantity of genetic diversity may be profoundly influenced by the emergence and dynamics of social groups. Permanent social living in spiders has resulted in the subdivision of their populations in more or less isolated colony lineages that grow, proliferate and become extinct without mixing with one another. A newly discovered hypervariable mitochondrial DNA region allowed us to examine the fine scale metapopulation structure in the social Anelosimus eximius. We sampled 39 colonies in Ecuador and French Guiana and identified 25 haplotypes. The majority of colonies contained one haplotype. Additional haplotypes occurred in approximately 15% of the colonies, and were always closely related to the common colony haplotype. Our findings confirm that colonies consist of single matrilines, with within-colony variation explained by mutations within the matriline. We thus found no evidence of mixing of matrilines. Likewise, colonies in a cluster often shared a haplotype, implying common colony ancestry. In few cases, however, haplotypes were shared between more distant colonies, providing evidence for occasional longer distance dispersal and/or widespread colony lineages. The geographical localities of colonies were incongruent with phylogenetic trees and haplotype networks, showing that some areas contained two or more matrilines. Hence, females do not migrate into foreign colonies, but faithfully remain within their own colony lineage, even when they disperse into new areas. These results indicate that the fine scale metapopulation structure of pure matrilines is maintained over the long term and that colony turnover is not extensive or radical enough to homogenize entire geographical areas. Genetic diversity is thus preserved to some extent at the metapopulation level.

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